The Venetian Macau took legal action in a Hong Kong court this week to recover about $4.5 million in the two separate cases.

In one lawsuit filed on Wednesday with Hong Kong’s High Court, the Venetian is trying to recover 23.4 billion Hong Kong dollars ($3 million) from Zou Yunyu. Zou once featured on lists of China’s richest people with a fortune from her company, the Shanghai Gaoyuan Property Group, that Forbes estimated in 2008 was worth $220 million.

In the second case, filed the same day, the Venetian is pursuing HK$11.3 million ($1.5 million) from Xie Xiaoqing, who Hong Kong media reports said Friday was a businessman and deputy to the provincial legislature in Hubei province.

The Venetian is one of four casinos owned by the Chinese arm of Adelson’s Las Vegas Sands Corp. in Macau, which became the world’s biggest casino market after the government ended a monopoly a decade ago. The former Portuguese colony, now a special administrative region of China, earned $38 billion in casino revenue in 2012, 13.5 percent higher than the year before.

Macau’s rise to the top has been powered by wealthy mainland Chinese gamblers but the lawsuits highlight the difficulties in collecting debts if they return to the mainland, where gambling is illegal and debts aren’t recognized by courts. Both Macau and nearby Hong Kong have separate legal systems from mainland China.

Still, the debts are a drop in the bucket for Las Vegas Sands, which reported net profit of about $350 million in the third quarter, with more than 90 percent of that coming from Sands China, its Macau unit.